Proportioning Valve - Brake fittings... size? 4w Disks

Does anyone know the size of the factory brake fittings on a 79K5? I am removing the factory PV combination valve and need to add a "T" on the front lines and a adjustable valve on the rear. I found numerous posts on the fittings, valves and such but none of them had an actually size of the lines coming in and out.

I just got done removing the factory PV and heck dang near all te lines are different sizes. I am going to head off the the parts store and see If I can find a t. The inlet is larger then the 2 outlets on the front lines. The rear line is larger on the outlet side so this might get tricky.

I was hoping to remove the factory PV and "T" the front lines together and run a adjustabe valve right off the MC for the rear. But I am not sure if I am going to find a reducer/coupler for the rear line. Might be looking at running new rear lines.

Anyone have a clue? It looks like there has been 100 different ways to do this but not many people have exact measurements or parts listed.

All the "skinny" tube (all the front stuff) is 3/16, the single line to the back is 1/4. You can get all the fittings you need at any GOOD parts store, the little tiny checkers and kragens are hurting on brake fitting stuff, I've had the best luck with the big pep boys here, or theres always Napa (the home mechanics stupid mistake saviour).

Your right about the TUBING being 3/16 on the "skinny stuff",and the line to the rear brakes is 1/4"...but the FITTINGS are often "Weird" sizes..many of the Proportioning Valves I had to change brake lines on had 3/16 lines with threaded fittings the same size as what a 1/4 line normally used!..or some other odball thread..

I often had to save the old fitting by cutting the line and use a 6 point socket to get it off---then cut and re-flare the new line,a big pain in the butt--some parts stores sell brake lines with the 2 different sized fittings on them--but they are few and far between--good luck finding any..

Some had a strange 9/16x20 machine screw thread on the fittings-,as do many GM master cylinders!--you know,the ones that dont come with that brass adapter dewhickey your old one didn't use--and your changing it on a sunday,when all the "real" parts stores are closed??..

Ok no luck on finding the needed parts, but I did get some measurements.

The front inlet is 5/16 the two front outlets are 3/16

The rear inlet is 1/4 but no luck on the outlet size???? It was not 1/4, 3/16, 5/16, or 3/8 which was the only lines they had available at parts store in the po-dunk town of Hobbs.

I think I might get a PV from a Disk/Disk I found a reference to AC Delco part number 172-1361 which came off a 1980-1994 P30 van. Neither Checker nor Autozone had PV valves for the P30 vans. I wish I could confirm the AC Delco part would bolt up before I drop 100.00 I think this is the part used in the Offroad Unlimited kit below. Now one of the things that concerns me here is that AC Delco lists the 172-1361 as mounted on the front of the brake booster. They also have a 172-1360 that is not listed as mounted on the front of the brake booster

Off to do more research. I never thought one of the most frustrating and time consuming parts of this buildup would be the brakes. I should have done them before I got the running gear up since it down blows that I can't go crawling.

Ok after a full night of searching and reading posts I came up with a few new part numbers

The Inline Tube part should be a PR-101 and lists at 99.00

The GM part number should be a 1257225 and GM parts direct lists them for 40.96

Can anyone confirm the bolt up fit on these two pieces for a 79 K5?

I will spend the extra $ to get the inline tube which I have seen confirmed here as bolt up. But why pay twice as much if I can get the GM one to bolt up. It was cross referenced as the above posts P-30 van also. So just two different part numbers for the AC Delco and the GM numbers.

Thanks for the info I am going to add all the part numbers to the members list once I have confirmation. I went ahead and ordered the GM part before I got your reply. I will confirm or deny if it fits. Figured I would give it a try since it is the least expensive option.

So we now have confirmation on Bolt Up fit for the inline tube part and yours which I think is the same part.

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